401 on tracing setup: make sure it is the LangSmith key, not the Hub key

The problem

Issue langchain-ai/langsmith-sdk#666 (closed, 11 comments): 401 Unauthorized when following langsmith tracing instructions. Set LANGCHAINTRACINGV2=true, LANGCHAINENDPOINT='https://api.smith.langchain.com', LANGCHAINAPI_KEY. Still getting auth errors.

What to do

[sahellebusch (reporter)]: If you get 401s after following the tracing setup docs, check which key you pasted: it must be the regular LangSmith API key (LANGCHAINAPIKEY), not the LangChain Hub key. The reporter was using the Hub key by mistake and everything worked once swapped.

In the GitHub issue gh:langchain-ai/langsmith-sdk#666 (https://github.com/langchain-ai/langsmith-sdk/issues/666), the problem reported was: Issue langchain-ai/langsmith-sdk#666 (closed, 11 comments): 401 Unauthorized when following langsmith tracing instructions. Set LANGCHAINTRACINGV2=true, LANGCHAINENDPOINT='https://api.smith.langchain.com', LANGCHAINAPIKEY. Still getting auth errors. The verified resolution was: [sahellebusch (reporter)]: If you get 401s after following the tracing setup docs, check which key you pasted: it must be the regular LangSmith API key (LANGCHAINAPI_KEY), not the LangChain Hub key. The reporter was using the Hub key by mistake and everything worked once swapped.